Substrate containing case

ABSTRACT

A substrate containing case having an upper cover and a lower cover coupled to each other through hinges such that they can be opened/closed freely. Upper and lower supporting part of a substrate are provided at four corners of the upper and lower covers, projecting from the inner surfaces of the covers. The lower supporting part of the lower cover serves to position and support simultaneously two edges at each corner of the substrate on the lower surface side. When the upper cover is closed, two edges at each corner of the substrate on the upper surface side are secured by the upper supporting part of the upper cover, and thus the substrate is contained.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate storage case for storingand carrying a substrate such as a photo mask or a photo mask blank usedfor manufacturing a semiconductor element or a liquid crystal displayelement, and in particular, to a substrate storage case for storing andcarrying substrates one by one, which can store and carry even a photomask with a pellicle.

2. The Related Art of the Invention

In a conventional substrate storage case for storing and carryingsubstrates one by one, for example, a main body and a lid body areconnected through a hinge, a fixing member is provided on each innersurface of the main body and the lid member to fix a stored article,outer faces of portions where the main body and the lid body are jointedare adapted to be flush with each other, and the hinge and an engagementportion thereof are arranged at a position lower than the jointingportions (for example, refer to Japanese Examined Utility ModelPublication No. 6-30686). And there is known a storage case providedwith a case main body, a lid body, and a lid-fixing band to blockrocking of a substrate in the upper, lower, and longitudinal directionsby support projections such as pins opposed to each other, each providedon each surface of the case main body and the lid body, and asurrounding piece provided on the case main body (refer to JapaneseUnexamined Patent Publication No. 10-142773).

The substrate storage case described in Japanese Examined Utility ModelPublication No. 6-30686) has, however, the problem that when the lidbody is opened, a photo mask or the like is lifted together with themain body, so that contaminants caught therein easily attach to thephoto mask or the like, thereby producing defects in appearance, andfurther, the problem that since a support of the photo mask in the upperand lower directions is performed by directly holding a mask front faceand a mask back face with a columnar projection provided in a supportmember, the substrate is contaminated.

The substrate storage case described in Japanese Unexamined PatentPublication No. 10-142773 has the problem that since a front face and aback face of a substrate such as a photo mask is directly held andsupported with a support projection made of plastic, the substrate iscontaminated or the support projections such as the pins are damaged.

Recent miniaturization and high density in a pattern of a photo mask orthe like cause an increasing demand for high quality thereof, resultingin a strong demand for properties such as low generation of dusts,damage prevention, contamination prevention, and ease of use even in asubstrate storage case for the photo mask or the like.

As described above, the positioning and the supporting of the substratein the conventional storage case are carried out individually, thereforeeasily generating dusts, which causes the difficulty of maintaining thehigh quality of the substrate.

SUMMARY OF THE INVENTION

The present invention, from the foregoing problems, has an object ofproviding an inexpensive substrate storage case with cleaning and dryingcharacteristics thereto, which stores therein a substrate such as aphoto mask, wherein the substrate storage case prevents substrate damageduring the storing and carrying thereof and substrate contamination dueto dust generation inside the case, is easy to handle, and restricts thedust generation in putting in and taking out the substrate.

In order to solve the foregoing problems, a substrate storage case ofthe present invention is structured in such a manner that positioningand supporting of a substrate are carried out at the same time.

The present invention is provided with a substrate storage case forstoring therein a substrate with a top face and a bottom face and havinga shape corresponding to the substrate, the substrate storage caseincluding a bottom lid, and a top lid connected through a hinge to thebottom lid so as to open and close the bottom lid and forming anengagement part between the bottom lid and the top lid, wherein lowersupport parts are disposed in a plurality of positions of the bottomlid, each of the lower support parts being brought in contact with apair of edges of the substrate on a bottom face side thereof, and uppersupport portions are disposed in a plurality of positions of the toplid, each of the upper support parts being brought in contact with apair of edges of the substrate on a top face side thereof.

The present invention is provided with the substrate storage case,wherein each of the substrate and the substrate storage case may bepreferably formed in a square shape.

The present invention is provided with the substrate storage case,wherein each of the lower support parts and the upper support parts maypreferably include a pair of support portions in contact with the pairof the edges.

The present invention is provided with the substrate storage case,wherein each of the pair of the support portions in each of the lowersupport parts and the upper support parts may preferably include anoblique face in contact with the edge.

The present invention is provided with the substrate storage case,wherein the lower support parts of the bottom lid and the upper supportparts of the top lid may be preferably positioned symmetrically witheach other and have shapes symmetrical with each other.

The present invention is provided with the substrate storage case, whichmay preferably further include a lock part disposed on a side of thebottom lid lower than a center in the thickness direction of the case tolock the bottom lid and the top lid, wherein the hinge is positioned ona side of the top lid higher than the center in the thickness directionof the case.

The present invention is provided with the substrate storage case,wherein the engagement part between the bottom lid and the top lid maypreferably extend obliquely and downwards from the hinge toward the lockpart, and a space may be preferably formed under the substrate on a sideof the lock part of the bottom lid to insert a finger of an automatictransport arm.

The present invention is provided with the substrate storage caseincluding a step portion which may be preferably provided in an outerface of each of four corners in each of the bottom lid and the top lid,the step portion being configured to come down from the other part.

The present invention is provided with the substrate storage case whichmay preferably further include a clamp member provided between the stepportion of the bottom lid and the step portion of the top lidcorresponding to the step portion of the bottom lid, wherein the clampmember clamps and also stands the bottom lid and the top lid.

The present invention is provided with the substrate storage case,wherein concave and convex portions in the bottom lid and the top lidmay preferably have round shapes.

The present invention is provided with the substrate storage case,wherein each of the bottom lid and the top lid may be preferably formedof conductive plastic.

The present invention is provided with the substrate storage case,wherein each of the lower support parts may be preferably formedintegrally with the bottom lid, and each of the upper support parts maybe preferably formed integrally with the top lid.

According to a substrate storage case of the present invention, thepositioning and the supporting of the substrate are carried out at thesame time by two edges each on the top face side and on the bottom faceside of each of the four corners in the substrate, whereby a front faceand a back face of the substrate such as a photo mask are not directlyheld down, so that substrate damage or substrate contamination due todust generation inside the case during the storing and the carryingthereof is prevented.

And when the top lid is opened, the bottom lid on which the substrate isplaced is not lifted with the top lid, and dust generation in putting inand taking out the substrate is restricted, thereby providing an effectof excellent cleaning and drying characteristics in regard to the caseitself.

Further, the lower support parts and the upper support parts of thesubstrate are respectively formed integrally with the bottom lid and thetop lid, thereby reinforcing rigidity in the lower support parts and theupper support parts and preventing failures thereof. As a result, damageto and contamination of the substrate due to the failures of the supportparts are prevented. And the lower support parts on the bottom lid aresymmetrical with the upper support parts on the top lid, thereby easilyforming the storage case and providing an inexpensive substrate storagecase.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a state where a substrate storage case isopened in a first preferred embodiment of the present invention.

FIG. 2 is a side cross sectional view taken along lines A-A in thesubstrate storage case shown in FIG. 1.

FIG. 3 is a perspective view showing upper support parts and lowersupport parts on the substrate storage case in the first preferredembodiment of the present invention.

FIG. 4 is a side cross sectional view showing a state where a substratestorage case is closed in the first preferred embodiment of the presentinvention.

FIG. 5 is a side view showing a state where a substrate storage case isclosed in the first preferred embodiment of the present invention.

FIG. 6 is a plan view showing a state where a substrate storage case isclosed in a second preferred embodiment of the present invention,wherein each of four corners of the substrate storage case is thinnerthan an entirety thereof.

FIG. 7 is a side view showing a state where a substrate storage case isclosed in the second preferred embodiment of the present invention,wherein each of four corners of the substrate storage case is thinnerthan an entirety thereof.

FIG. 8 is a plan view showing a state where each of the four corners ofthe substrate storage case in FIG. 6 is clamped by a clamp member.

FIG. 9 is a side view showing a state where each of the four corners ofthe substrate storage case in FIG. 7 is clamped by the clamp memberwhich funetions as a case stand, and the substrate storage case isplaced vertically.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be explained withreference to the drawings as follows.

FIG. 1 is a plan view showing a state where a substrate storage case 1is opened in a first preferred embodiment of the present invention, andFIG. 2 is a side cross sectional view taken along lines A-A in thesubstrate storage case shown in FIG. 1.

As shown in FIGS. 1 and 2, a substrate storage case 1 stores therein apolygonal (quadrangular) substrate 7 having a top face 7 a and a bottomface 7 b, and has a polygonal (quadrangular) shape corresponding to thesubstrate 7. The substrate storage case 1 is provided with a bottom lid3 and a top lid 2 connected through a hinge 4 to the bottom lid 3, andis provided with an engagement portion 13 formed between the bottom lid3 and the top lid 2.

The substrate 7 has four edges 7 c on the top face 7 a and four edges 7c on the bottom face 7 b.

The substrate 7 stored in the substrate storage case 1 of the presentinvention is a substrate such as a photo mask (to be also referred to asreticle) or a photo mask blank used for manufacturing a semiconductorelement or a liquid crystal display element, and a substrate made mainlyof low thermal expansion glass or silica glass with a light shieldingfilm. A main face provided typically with the light shielding film or apattern has a square shape. A profile dimension of the substrate isdefined by the standard. With regard to the substrate 7 in the presentinvention, a substrate with pellicle may be stored by thickening thestorage case 1.

As described above, the top lid 2 and the bottom lid 3 are connectedwith each other through the hinge 4 so as to be opened and closed. Thehinge 4 of the present invention is detachable. Therefore, the top lid 2can be easily removed from the bottom lid 3 through the hinge 4 byopening the top lid 2 with respect to the bottom lid 3 at approximately270 degrees. The substrate storage case 1 is so configured that the toplid 2 is easily mounted to the bottom lid 3 again through the hinge 4 atthe angle where the top lid 2 has been removed from the bottom lid 3through the hinge 4. Thus it is easy to wash and dry the lids 2, 3separately at the time of case cleansing or the like.

Each of four upper support parts 5 for substrate is provided in each ofthe four corners on the inner face of the top lid 2, and each of fourlower support parts 6 for substrate is provided in each of the fourcorners on the inner face of the bottom lid 3. Each of the upper supportparts 5 and the lower support parts 6 can be formed separately from thecorresponding lids 2, 3, but it is preferable for accomplishing easyformation, and strength and accuracy of the support parts that each ofthe upper support parts 5 and the lower support parts 6 is formedintegrally with the corresponding lids 2, 3.

Each of the upper support parts 5 and the lower support parts 6 for thesubstrate is provided with a pair of support portions 5 a and a pair ofsupport portions 6 a, each pair having a generally L-shape forsupporting a pair of edges 7 c of the substrate 7. The cross angle ofeach of the pair of the support portions 5 a and 6 a, each pair havingthe generally L-shape, is 90 degrees. The length of the support portion5 a is not necessarily equal to that of the support portions 6 a.However, since the main face of the substrate such as the photo masktypically has a square shape, the lengths of the support portions 5 aand 6 a are preferably equal with each other to form the symmetry havingno directness in geometry. Note that in the case of supporting acircular substrate, support portions 5 a and 6 a corresponding to theconfiguration of the circular substrate 7 are provided, thereby the sameeffect as that of the substrate 7 in a generally L-shape can be made. InFIG. 3, the lower support parts 6 only are shown for convenience, butthe upper support parts 5 have substantially the same structure as thatof the lower support parts 6.

In the present invention, each of the support portions 5 a and 6 ahaving the generally L-shape to support the substrate 7 has an obliqueface and is configured so as to contact only the edge 7 c on one side ofthe substrate 7. In FIGS. 1 and 2, the substrate 7 is placed on thesupport part 6 respectively in the four corners of the bottom lid 3, sothat edges 7 c in each of the four corners on the bottom face 7 b of thesubstrate 7 are brought respectively in contact with two oblique faces11 of the support portions 6 a, thus the substrate 7 can be positionedand supported by the oblique faces 11 of the support portions 6 a. Thatis, the substrate 7 is securely supported at the two neighboring edges 7c crossed to each other in each of the four corners of the bottom face 7b of the substrate 7 by the eight lower support portions 6 a of thelower support parts 6.

The lower support parts 6 for the substrate 7 in the present inventionwill be explained in more detail. FIG. 3 is a perspective view showingone example of the lower support parts 6 on four corners of the bottomlid 3 of the substrate storage case 1.

Each of the support portions 6 a supporting the edges 7 c of thesubstrate 7 and surrounded by two sections in a L-shape has an obliqueface 11. An angle of the oblique face 11 may be an angle at which thesubstrate 7 can be positioned and supported, which is in the range of 15degrees to 75 degrees with respect to the bottom face of the bottom lid3. When an angle of the oblique face 11 is less than 15 degrees, thesupport strength for the substrate 7 is not sufficient due to such smallangle and reoccurrence of the same support position is reduced. When anangle of the oblique face 11 exceeds 75 degrees, degrees of freedom tothe dimensional tolerance in size of the substrate 7 becomeinsufficient, possibly causing in damages of the substrate 7. Morepreferably an angle of the oblique face is in the range of 30 degrees to60 degrees for heightening a mechanical strength of the support part 6,support characteristics for the substrate 7, dispersion characteristicsof forces applied on the substrate 7, and degrees of freedom in size ofthe substrate 7. Furthermore preferably, an angle of the oblique face 11is 45 degrees so that forces applied on the substrate 7 in the verticaland longitudinal directions can become equal.

In the present invention, as shown in FIG. 3, in order to preventcontact between the substrate 7 and the substrate storage case 1 causedby deviations of the substrate 7 and to relieve stresses generated inthe support portion 6 a for the edge 7 c of the substrate 7, a space 12is preferably provided at a crossing point between the support portions6 a as two sides in a generally L-shape. FIG. 3 shows an example wherethe space 12 is provided by removing a resin in a columnar shape in thevicinity of the crossing point between the two support portions 6 a in agenerally L-shape.

Further, in the present invention two support portions 6 a may beseparated from each other and crossed at 90 degrees to form a mountainshape (formed by two unparalleled sections). However, the generallyL-shape as described above is preferable for improving strength of thelower support part 6. Note that the upper support part 5 is provided ina position on the top lid 2 corresponding to the lower support part 6,and is substantially the same structure of the lower support part 6.

Next, by closing the top lid 2, two edges 7 c in each of the fourcorners on the top face 7 a of the substrate 7 can be respectivelybrought in contact with two oblique faces 11 of the upper support part 5to support and clamp the substrate 7. That is, the substrate 7, as issimilar to a side of the bottom face 7 b, is supported and fixed on theeight support portions 5 a of the upper support parts 5 at two edgescrossed and neighbored in each of the four corners on the top face 7 a.

FIG. 4 is a side cross sectional view showing a state where the top lid2 is closed.

As shown in FIG. 4, the substrate 7 is clamped in such a manner that theedges 7 c in the four corners on each of the top and bottom faces 7 aand 7 b thereof are positioned both at the oblique faces 11 provided inthe support portions 5 a of the upper support parts 5 on the top lid 2and at the oblique faces 11 provided in the support portions 6 a of thelower support parts 6 on the bottom lid 3, whereby at the same time, thesubstrate 7 is prevented from moving in the vertical and longitudinaldirections. The substrate 7 does not move by vibrations generated duringthe shipping thereof, and as a result, the substrate 7 can not bedamaged and contamination of the substrate 7 due to dust generation cannot be generated.

FIG. 5 is a side view showing a state where the substrate storage casein the first preferred embodiment of the present invention, is closed.As shown in FIG. 5, in the present invention the hinge 4 is provided ata position higher than a center of the thickness direction of thesubstrate storage case 1, and lock parts 9 and 10 to lock the top lid 2and the bottom lid 3 are provided at a position lower than the hinge 4.Accordingly, an engagement part 13 between the top lid 2 and the bottomlid 3 of the substrate storage case 1 has an oblique part extendingobliquely and downwards from the hinge 4 toward the lock parts 9 and 10.

The substrate storage case according to the present invention is soconfigured as described above. Thus, as shown in FIG. 2, when the toplid 2 of the substrate storage case 1 is opened, a hinge side of thebottom lid 3 is not lifted. Therefore, in the present invention, theredoes not occur the problem that dusts in the circumstance of thesubstrate storage case 1 becomes poor involved therein due to the hingeside of the bottom lid 3 being lifted or that an appearance of thesubstrate storage case 1 becomes poor by attachment of foreign materialsto the substrate 7 like the conventional case. In the preferredembodiment shown in FIG. 2, the top lid 2 is opened at an angle ofapproximately 185 degrees away from a point where the top lid 2 isclosed.

Further, in the present invention, the lock parts 9 and 10 are providedat a position lower than the center in the thickness direction of thesubstrate storage case 1 in addition to the configuration in FIG. 5 asdescribed above. When the top lid 2 is opened, a space 7 s in size largeenough for a finger of an automatic transport arm to be inserted isprovided under the substrate 7. As a result, when the top lid 2 isopened to take out the substrate 7 therein, the finger of the automatictransport arm can be inserted under the substrate 7, and therefore thesubstrate 7 in the substrate storage case 1 can be putted in or takenout without aid of persons. Further, hooks of the lock parts 9 and 10are adapted to be opened and closed by the automatic transport arm,thereby the putting in and the taking out of the substrate 7 in thesubstrate storage case 1 can be automatically made, and therefore of thesubstrate storage case 1 can be securely transported.

As shown in FIGS. 6 and 7, the thickness in each of the four corners inthe substrate storage case 1 including the upper support parts 5 and thelower support parts 6 may be thinner than that of the entirety of thesubstrate storage case 1.

FIG. 6 is a plan view showing a state where a substrate storage case isclosed in a second preferred embodiment of the present invention,wherein the thickness in each of the four corners of the substratestorage case 1 including the upper support parts 5 and the lower supportparts 6 is thinner than that of the entirety thereof. FIG. 7 is a sideview in FIG. 6. In FIGS. 6 and 7, components identical to those in FIGS.1, 2, and 5 are referred to as identical numerals.

In FIGS. 6 and 7, a step portion 14 is formed by making an outer face ofeach of four corners in each of the top lid 2 and the bottom lid 3 ofthe substrate storage case 1 thinner. By forming the thinner outer facesin the four corners, the photo mask can be easily stored in thesubstrate storage case 1, and the case 1 can be securely locked. Theheight of each of the support parts 5 and 6 can be lowered because thefour corners include the support parts 5 and 6, as a result the supportparts 5, 6 can improve rigidity thereof as the support member. Since thestep portion 14 is provided at the four corners, the substrate storagecase 1 can be fixed, not at the outermost periphery, but at an inside ofthe substrate storage case 1 (closer to the support parts 5 and 6),thereby no influence of dust generation will not occur due to theapparatus.

FIG. 8 is a plan view showing a state where the four corners of thesubstrate storage case 1 in FIG. 6 are clamped by clamping members 15.In the present invention, the clamping members 15 are fixed to the stepportions 14 provided in the four corners of the substrate storage case 1as shown in FIG. 8, whereby it is possible to securely lock the top lid2 and the bottom lid 3. Since the thickness in the four corners of thesubstrate storage case 1 is thinner, it is easy to mount and remove theclamping members 15. Furthermore, it is possible to make the thicknessin the four corners including the thickness of the clamping member 15after the mounting be within the range of the thickness of an entiresubstrate storage case 1. As a result, the clamping member 15 does notcause an obstacle in storing and carrying the substrate storage case 1.

The clamping member 15 may be formed of plastic, rubber, a metallicclipper, or a fixture band.

Further, FIG. 9 is a side view showing a state where each of the fourcorners of the substrate storage case 1 in FIG. 7 is clamped by theclamp member 15 which functions as a case stand and the substratestorage case 1 is placed vertically. The substrate storage case 1 of thepresent invention, as shown in FIG. 9, can be vertically arranged neatlylike books in a mask storage shelf or the like by using the clampingmember 15 functioning as a case stand. When an IC tag or the like isattached to an outside of the substrate storage case 1, it is possibleto automatically put in and take out the substrate storage case 1 in theshelf. In addition, the substrate storage case 1 can be automaticallytransported and the substrate 7 can be automatically put in and takenout the substrate storage case 1. As a result, manual labors can bereduced to reduce a quality problem due to dusts, and quality andproductivity of the substrate 7 can be improved, thus manufacture,transport, and storage of a high-quality mask can be accomplished.

It is preferable that a material of each of the top lid 2, the bottomlid 3, the support parts 5 and 6 is recyclable with a low dustgeneration, good cleansing characteristics, and good dryingcharacteristics. When the substrate storage case 1 is charged during theshipping thereof or the like, a photo mask pattern may be destroyed dueto electric discharge phenomenon or the substrate 7 may be contaminatedby absorbing dusts in the air. Accordingly, it is preferable that eachof the top lid 2, the bottom lid 3, the support parts 5 and 6 is made ofconductive plastic. Such conductive plastic may be formed of a resin,for example, a product name “BAYON” (made by Kureha Chemical IndustryCo., Ltd.) or Novalloy (made by Daicel Polymer Co., Ltd.) having astructure where rubber particles with a small electrical resistance aredispersed in the hard resin.

A gasket 8 used as packing in the engagement portion 13 between the toplid 2 and the bottom lid 3 may be formed of fluorinated rubber, forexample, a product called Fluoroplas (made by NICHIAS Corp.).

In the present invention, the gasket 8 in a convex shape is provided onthe engagement portion 13 of the top lid 2 to be engaged therein and theengagement portion 13 of the bottom lid 3 corresponding to the gasket 8is formed in a concave shape, thereby the engagement portion can besecurely sealed. Another engagement portion can be provided in an insideof the gasket 8. Accordingly, in a state where the lock parts 9 and 10are unlocked, even if the sealing property of the gasket 8 is notmaintained, the engagement portions are partly overlapped, thuspreventing the foreign materials from entering an inside of thesubstrate storage case 1 from an outside. As a result, it is notnecessary to bond the engagement portions of the top lid 2 and thebottom lid 3 with a tape after storing the substrate 1 into thesubstrate storage case 1 like the conventional storage case.

In the present invention, the gasket 8 also serves as a buffer materialwhen the top lid 2 is put on top of the bottom lid 3.

The substrate storage case 1 according to the present invention is sostructured that the top lid 2 and the bottom lid 3 are detachable fromeach other due to the hinge 4 and the lock parts 9 and 10 are providedand locked at one position or more. However, the substrate storage casemay be so structured that, for example, the lock parts 9 and 10 areprovided at two positions, and locked by a hook when the top lid 2 andthe bottom lid 3 are engaged, and the lock parts 9 and 10 are unlockedby pushing the hook.

At the time of opening the top lid 2 and the bottom lid 3 of thesubstrate storage case 1 which has stored the substrate 7 therein, thepattern face of the substrate 7 is preferably directed downwards inorder to avoid dropping and attachment of dusts to the pattern face fromthe surroundings. The substrate storage case 1 of the present inventionmay be manufactured in such a manner that the top lid 2 and the bottomlid 3 are symmetrical except for the hinge 4 and the lock parts 9 and10. Therefore, the substrate storage case 1 can be opened from bothsides of the top lid 2 and the bottom lid 3 and it is advantageous thatin the inside process of a photo mask manufacture or the like, the toplid 2 and the bottom lid 3 can be optionally opened as needed.

In the substrate storage case 1 of the present invention, it ispreferably to eliminate blowholes at resin molding of the storage caseand to avoid generation of, dusts in corner portions and concave andconvex portions. In order to accomplish the above, it is furtherpreferable that the corner portions and the concave and convex portionshave round shapes to easily wash and dry the substrate storage case 1.

Since the substrate storage case 1 of the present invention can bemanufactured in such a manner that the top lid 2 and the bottom lid 3are formed integrally with the substrate support parts 5 and 6, aninexpensive substrate storage case with high rigidity and high qualitycan be provided. Further, since only conductive materials are used inportions of the case which the substrate 7 is directly in contact with,it is prevented for the substrate 7 to be influenced by an extramaterial.

Further, the substrate storage case of the present invention is providedwith a bar code label or an IC tag at an outer surface thereof andtherefore, product management for each substrate storage case can bemade.

EXAMPLE 1

Next, detailed example of the above-described preferred embodiments willbe explained.

In order to manufacture a substrate storage case used exclusively for aphoto mask of six inches (an outside dimension: 6×6×0.25(thickness)inches), a mold for the top lid 2 and the bottom lid 3 of the case 1 (anoutside dimension: 220×230×22 (thickness)mm) including the hinge 4 andthe lock parts 9 and 10 was produced. The top lid 2 and the bottom lid3, each having the resin thickness of 3 mm, were produced using Novalloy(brand name) resin (made by Daicel Polymer Ltd.). A convex engagementportion was provided at a portion of the top lid 2 where the top lid 2and the bottom lid 3 are engaged, the convex engagement portion being asthe gasket 8 made of polyester elastomer resin, and a concave engagementportion was formed at the corresponding portion of the bottom lid 3. Thehinge 4 was provided in such a manner that the top lid 2 and the bottomlid 3 were detachable. The lock parts 9 and 10 were provided at twolocations, whereby when the top lid 2 and the bottom lid 3 were engaged,they were locked by the hook and were unlocked by pushing the hook.

At four corners on the inner face of each of the top lid 2 and thebottom lid 3, the four support parts 5 and the four support parts 6 wererespectively integral with the top lid 2 and the bottom lid 3. Each ofthe support parts 5 and 6 had a size of 30×30×10 (height)mm and wasprojected from the inner face in each of the top lid 2 and the bottomlid 3. Each of the support portions 5 a and 6 a in a L-shape for thesubstrate edge 7 c, having a dimension of 20×20×20 (height from thebottom face of the lid)mm was further projected at each corner in aninside of each of the support parts 5 and 6. Each of the support parts 5and 6 was integral with each of the top lid 2 and the bottom lid 3. Eachof the support portions 5 a and each of the support portions 6 a for thesubstrate edge 7 c, each surrounded by two sides in a L-shape crossed at90 degrees, had an oblique face 11 formed at each of the two sides, andan angle of the oblique face 11 is 45 degrees to the inner face of thecorresponding lid. The columnar space 12 was provided at a crossingpoint of the two sides in a L-shape. The top lid 2 and the bottom lid 3were symmetrical in the upper and lower directions except for the hinge4 and the lock parts 9 and 10 to form the substrate storage case 1.

Next, the photo mask 7 of six inches (an outside dimension:6×6×0.25(thickness) inches) was placed on the bottom lid 3 of thestorage case 1 when the above top lid 2 is opened, with the pattern faceof the photo mask 7 being directed downwards. Two edges 7 c on thebottom face 7 b of the mask 7 in each of the four corners wererespectively in contact with two oblique faces 11 of the support portion6 a, so that the mask 7 was securely positioned and supported. As aresult, the mask 7 was supported on the eight oblique faces 11 of thesupport parts 6 by the two neighboring edges crossed vertically in eachof the four corners on the bottom face 7 b.

Next, the top lid 2 was closed and locked, whereby the two edges 7 c ineach of the four corners on the top face 7 a of the mask 7 were broughtin contact with the two oblique faces 11 of the support parts 5 on thetop lid 2 so that the mask 7 was supported and fixed. Namely, the photomask similarly to the bottom face 7 b, was also supported and fixedsecurely on the eight oblique faces 11 by the two neighboring edges 7 ccrossed vertically in each of the four corners on the top face 7 a.

COMPARISON EXAMPLE 1

By the conventional art, the storage case (225×225×41 mm) for the photomask of six inches was produced, the top lid and the bottom lid of whichwere made of BAYON resin and was able to be separated from each other.This storage case was provided with an outer periphery-fixing portionfor positioning an outer periphery of the mask and a pin-shapedprojection made of BAYON for fixing the mask, the fixing portion and theprojection being provided in each of the top lid and the bottom lid, tosupport the mask. A top end of the pin-shaped projection as a contactportion with the mask was covered with silicon resin to soften theimpact at the time of the contacting. The photo mask of six inches wasplaced on the storage case with the pattern face of the photo mask beingdirected downwards and fixed by the upper and lower pins. Next, theengagement portions of the top and bottom lids were sealed with wrappingtapes and clamped in the four corners by resin clips.

Comparison of Dust Generation Characteristics

A forced dust generation test was carried out in the same condition foreach of the substrate storage case of the present invention in Example 1and the conventional substrate storage case in Comparison Example 1 tocompare the comparison generation characteristics. The measurementcondition: a photo mask was stored in each of the substrate storage caseof the present invention and the conventional substrate storage case,which thereafter, were vibrated for two hours. A size (μm) of a foreignmaterial on each mask was measured before each mask is stored and aftereach mask was stored and vibrated, to compare an increased number of theforeign materials by a foreign material measurement apparatus of laserreflective type GM (made by Hitachi, Ltd.). The measurement area was130×130 mm and an averaging value was determined by carrying out thedust generation test with regard to the four masks in each of thestorage case of the present invention and the conventional storage case.As a result, it is found that an amount in the dusts generated in thestorage case of the present invention is 1/7 of that in the conventionalstorage case.

1. A substrate storage case for storing therein a substrate with a top face and a bottom face and having a shape corresponding to the substrate, comprising: a bottom lid; and a top lid connected through a hinge to the bottom lid so as to open and close the bottom lid and forming an engagement part between the bottom lid and the top lid, wherein: lower support parts are disposed in a plurality of positions of the bottom lid, each of the lower support parts being brought in contact with a pair of edges of the substrate on a bottom face side thereof; and upper support portions are disposed in a plurality of positions of the top lid, each of the upper support parts being brought in contact with a pair of edges of the substrate on a top face side thereof.
 2. The substrate storage case according to claim 1, wherein: each of the substrate and the substrate storage case is formed in a square shape.
 3. The substrate storage case according to claim 2, wherein: each of the lower support parts and the upper support parts includes a pair of support portions in contact with the pair of the edges.
 4. The substrate storage case according to claim 3, wherein: each of the pair of the support portions in each of the lower support parts and the upper support parts includes an oblique face in contact with the edge.
 5. The substrate storage case according to claim 1, wherein: the lower support parts of the bottom lid and the upper support parts of the top lid are positioned symmetrically with each other and have shapes symmetrical with each other.
 6. The substrate storage case according to claim 1, further comprising: a lock part disposed on a side of the bottom lid lower than a center in the thickness direction of the case to lock the bottom lid and the top lid, wherein: the hinge is positioned on a side of the top lid higher than the center in the thickness direction of the case.
 7. The substrate storage case according to claim 1, wherein: the engagement part between the bottom lid and the top lid extends obliquely and downwards from the hinge toward the lock part; and a space is formed under the substrate on a side of the lock part of the bottom lid to insert a finger of an automatic transport arm.
 8. The substrate storage case according to claim 2, wherein: a step portion is provided in an outer face of each of four corners in each of the bottom lid and the top lid, the step portion being configured to come down from the other part.
 9. The substrate storage case according to claim 8, further comprising: a clamp member provided between the step portion of the bottom lid and the step portion of the top lid corresponding to the step portion of the bottom lid, wherein: the clamp member clamps and also stands the bottom lid and the top lid.
 10. The substrate storage case according to claim 1, wherein: concave and convex portions in the bottom lid and the top lid have round shapes.
 11. The substrate storage case according to claim 10, wherein: each of the bottom lid and the top lid is formed of conductive plastic.
 12. The substrate storage case according to claim 1, wherein: each of the lower support parts is formed integrally with the bottom lid; and each of the upper support parts is formed integrally with the top lid. 